000 FXUS63 KLSX 100851 AFDLSX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ST LOUIS MO 251 AM CST FRI FEB 10 2012 .SHORT TERM... ISSUED AT 241 AM CST FRI FEB 10 2012 (TODAY) STRONG CDFNT EXTENDING FROM A SFC LOW OVER NRN WI SW THROUGH EXTREME NWRN MO WILL MOVE SEWD THROUGH OUR FORECAST AREA TODAY. STRONG AND GUSTY NWLY SFC WINDS BEHIND THIS CDFNT WILL BRING MUCH COLDER AIR SEWD INTO OUR AREA TODAY. HIGH TEMPERATURES ACROSS NERN MO AND W CNTRL IL WILL OCCUR THIS MRNG WITH FALLING TEMPERATURES THIS AFTN. THE MODELS WERE DROPPING THE -16 DEGREE C 850 MB ISOTHERM SWD INTO NERN MO BY 00Z SAT. TEMPERATURES FURTHER S WILL RISE THIS MRNG LIKELY REACHING THE MAXIMUM VALUE AROUND NOON OR SHORTLY AFTER THEN FALL DURING THE LATE AFTN AFTER FROPA. LIGHT PRECIPITATION WAS SPREADING EWD THROUGH SWRN MO AHEAD OF A SHORTWAVE TROUGH OVER ERN KS AND CNTRL OK. THE MODELS WERE PRETTY CONSISTENT IN GENERATING MOST OF THE PRECIPITATION ACROSS SRN MO MAINLY S OF STL THIS MRNG...THEN MAINLY ACROSS SERN MO SWRN IL THIS AFTN...SE OF STL. PRECIPITATION AMOUNTS SHOULD BE LIGHT BUT MAY BE IN THE FORM OF SNOW EARLY THIS MRNG WITH TEMPERATURES IN THE MIDDLE 30S. AS SFC TEMPERATURES RISE AHEAD OF THE CDFNT THE PRECIPITATION SHOULD BE MAINLY IN THE FORM OF LIGHT RAIN...BUT THEN MAY CHANGE BACK TO LIGHT SNOW LATE THIS AFTN AS THE TEMPERATURES FALL RAPIDLY BEHIND THE CDFNT. ANY ACCUMULATIONS SHOULD BE LIGHT...MAYBE A DUSTING AND MAINLY ON GRASSY AREAS RATHER THAN ON THE ROADS. GKS && .LONG TERM... ISSUED AT 249 AM CST FRI FEB 10 2012 (TONIGHT THROUGH THURSDAY) VERY COLD WEEKEND ON TAP AS 1045MB ARCTIC HIGH PRESSURE BUILDS SOUTH ACROSS THE PLAINS AND INTO THE MIDWEST. UPSTREAM OBSERVATIONS ACROSS THE UPPER MIDWEST AND SOUTHERN CANADA SUPPORT COLDEST GUIDANCE AVAILABLE AS STRONG COLD AIR ADVECTION IS ANTICIPATED TO DRIVE TEMPERATURES TO THEIR LOWEST READINGS OF THE SEASON. NEXT SHORTWAVE OF INTEREST IS CURRENTLY LOCATED ACROSS THE PACIFIC OCEAN AND IS NOT EXPECTED TO MAKE LANDFALL AND BE SAMPLED BY THE RAOB NETWORK UNTIL 12Z SATURDAY. REMARKABLY...THERE IS CONSENSUS AMONG THE MODEL GUIDANCE THAT THIS SHORTWAVE WILL BRING SNOW TO THE CWA EARLY NEXT WEEK. SURE...THERE ARE SOME SUBTLE TIMING AND PLACEMENT DIFFERENCES...BUT THEY ALL GENERALY HAVE THE SAME IDEA OF BROAD LIFT PRODUCING A FEW INCHES OF SNOW ON MONDAY. HAVE INCREASED POPS INTO THE LIKELY CATEGORY FOR THIS SYSTEM AND KNOCKED TEMPS BACK A FEW DEGREES ON MONDAY WITH EXPECTED CLOUD COVER AND PRECIPITATION. MODEL CONTINUITY ENDS IN THE WAKE OF THIS WITNER SYSTEM...WITH THE GFS DEPICTING ANOTHER STORM BRINGING RAIN TO THE AREA LATER IN THE WEEK...WHILE THE ECWMF DRIVES THE SHORTWAVE FURTHER SOUTH...KEEPING THE AREA DRY. HAVE MAINTAINED SOME LOW CHANCE POPS FOR WEDNESDAY NIGHT AND THURSDAY AND WILL WAIT FOR BETTER MODEL AGREEMENT. CVKING && .AVIATION... ISSUED AT 1117 PM CST THU FEB 9 2012 FCST WILL FOCUS ON CIGS THRU THE TAF PERIOD...PRECIP CHANCES ASSOC WITH AN APPROACHING SHORT WAVE AND GUSTY NW WINDS BEHIND A STRONG COLD FRONT THAT WILL PUSH THRU FRIDAY. CIGS WILL BEGIN TO DROP FRIDAY MORNING AS THE SHORT WAVE APPROACHES. THE BEST FORCING SHOULD REMAIN SOUTH OF THE TERMINALS WHICH WILL KEEP KCOU AND THE STL METRO TERMINALS ON THE NRTHRN EDGE OF THE PRECIP. THE CURRENT PRECIP SHIELD SHOULD MOVE ALONG THE MO/AR BORDER OVERNIGHT AND THEN BEGIN TO ADVANCE TO THE NE FRIDAY MORNING. DUE TO UNCERTAINTY ON THE NORTHWARD EXTENT OF THE PRECIP COVERAGE...OPTED TO KEEP VCSH FOR THE MORNING HOURS. KCPS HAS THE BEST CHANCE OF SEEING ANY PRECIP PRIOR TO 18Z. THE COLD FRONT IS ON TRACK TO PUSH THRU THE TERMINALS FROM MID MORNING TO MID AFTN. FORCING ALONG THE FRONT SHOULD GENERATE SOME LIGHT PRECIP AS WELL. THE PRECIP SHOULD START AS RAIN OR A RAIN/SNOW MIX AND COULD END AS ALL SNOW AS COLDER AIR FILTERS IN. ATTM...IT APPEARS ACCUMULATING SNOW IS UNLIKELY. VSBYS SHOULD DROP TO MVFR DURING THE PRECIP AND COULD DROP EVEN LOWER IF THE CHANGEOVER TO SNOW OCCURS SOONER THAN ANTICIPATED. THE COLD FRONT SHOULD PUSH THE BULK OF THE PRECIP SE OF THE TAF SITES BY MID AFTN...LEAVING FLURRIES FOR THE REST OF THE PERIOD. IFR CIGS ARE POSSIBLE ALONG AND BEHIND THE FRONT...BUT AM NOT CONFIDENT ENUF ATTM TO INCLUDE. NW WINDS WILL CONTINUE THUR THE NIGHT AS A STRONG SFC RIDGE BUILDS INTO THE AREA. SPECIFICS FOR KSTL...CIGS WILL LOWER FRIDAY MORNING DUE TO APPROACHING SHORT WAVE. KEPT VCSH FOR LATE MORNING DUE TO UNCERTAINTY ABOUT NORTHWARD EXTENT OF PRECIP DURING MORNING. ANOTHER BAND OF PRECIP SHOULD FORM ALONG THE FRONT DURING THE AFTN. THIS SHOULD START AS A RAIN OR RA/SN MIX AND COULD END AS ALL SNOW WITH COLDER AIR BEHIND THE FRONT. VSBYS MAY DROP TO IFR IF CHANGEOVER TO SNOW HAPPENS EARLIER THAN EXPECTED. CIGS MAY LOWER TO IFR TOMORROW AFTN IN ASSOC WITH THE COLD FRONT AND PRECIP...BUT AM NOT CONFIDENT ENUF TO INCLUDE ATTM. NW WINDS WILL INCREASE AS A 1040+ MB SFC HIGH BUILDS INTO THE AREA OVERNIGHT. MVFR IF NOT LOWER CIGS WILL PREVAIL THRU THE END OF THE FCST PERIOD. MILLER/TES && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX